Which of the following ions is known to have the formula CO3(2-)?

The ion with the formula CO3(2-) is known as carbonate. This polyatomic ion is composed of one carbon atom covalently bonded to three oxygen atoms. The overall charge of the ion is -2, indicating that it has two more electrons than protons. Carbonate is commonly found in nature, especially in carbon compounds and mineral formations. It plays a significant role in biological systems, such as the regulation of pH in biological fluids, and is also a key component in many geological processes, like the formation of sedimentary rocks.

Understanding the structure and charge of carbonate helps clarify its distinction from other similar ions. For example, the nitrate ion has the formula NO3(-), and hydroxide has the formula OH(-), which differ in both composition and charge. Cyanate, on the other hand, consists of carbon, nitrogen, and oxygen with a different structural configuration, represented by the formula OCN(-). Recognizing these characteristics allows you to identify carbonate uniquely among these choices.